The invention discloses a laser cladding coating for improving the water erosion resistance of brazed stellite and a preparation method. A coating is laser-cladded on the surface of a stellite substrate brazed on a steam turbine blade, the coating is composed of a continuous phase nickel-based alloy material and dispersion strengthening phase wolfram carbide particles, the WC particles are spherical, stress concentration caused by sharp corners is effectively eliminated, the coating cannot crack, wolfram oxide with certain thickness is arranged on the surfaces of the WC particles, excessive dissolution of a WC melted nickel-based alloy is avoided, optimum dispersion strengthening of a nickel-based alloy phase is achieved, the coating is prepared through the laser cladding technology, the efficiency is high, the operation is easy, and the prepared coating is dense, free of cracks and low in porosity. The laser cladding coating for improving the water erosion resistance of the brazed stellite and the preparation method of the laser cladding coating can be used for water-erosion-resistant coatings on the surfaces of blades of large nuclear steam turbines and thermal power steam turbines and manufacturing, repairing and re-manufacturing, the service performance of parts is effectively improved, and the service life of the parts is effectively prolonged.